The explosive growth in international long distance telecommunications, coupled with the adoption and implementation of national and international signaling standards, such as Common Channel Signaling 7 Network Interconnect (CCS7 NI), Primary Rate Interface (PRI) and Basic Rate Interface (BRI) of Integrated Services Digital Network (ISDN), have provided the impetus for the creation of a wide variety of sophisticated international communications services offered by IntereXchange Carriers (IXC). These services include database-queried toll-free international calling which allows subscribers to be reached by customers beyond their national borders, usually at no cost to the caller except for a possible local access fee in a limited number of countries.
While toll-free subscribers in the United States have become accustomed to a variety of information forwarding features (such as calling party number forwarding), these features have not heretofore been available in the international arena. Thus, in contrast to the domestic market, international toll-free subscribers have not been able to receive background information regarding calls originating outside of areas that use the North American Numbering Plan. This background information could, for example allow the subscriber to distinguish between the needs of different callers and offer personalized services based upon the country or location of call origination.
One attempt to provide international toll-free subscribers with caller location information, involves the use of the Originating Country Information (OCI) which is part of the billing data exchanged between switching points at call setup time for some international calls. Unfortunately, this approach limits the scope of OCI usage to routing and billing functions exclusively. More importantly, this method lacks the required flexibility needed to permit OCI processing in any standard fashion to enable delivery of that information to the international toll-free subscriber. Thus, at the present time, international toll-free subscribers cannot target specific international market segments or tailor customized services for their foreign callers. This deficiency takes a special significance when one considers cultural and language barrier issues, as well as currency and measurement scale differences between calling and called parties located in different countries.
To remedy this limitation, consideration is being given to utilization of the ISDN User Part (ISUP) signaling standard that has been adopted by the CCITT, to transmit before call completion, OCI or more specifically, Calling Line Identity (CLI) information between switching points. CLI information is comprised of an Originating Country Code (OCC) which is a one to three digit number assigned to each country by CCITT, a trunk code (similar to the area code in the North American Dialing Plan) and a calling party national telephone number. CLI information can be passed between international and local exchange carrier digital switches only over international trunks rigidly adhering to stringent CCITT7 signaling standards that define protocols for the transmission of supervisory and out-of-band signaling information. Thus, even though future deployment of CCS7/ISUP or CCITT7/ISUP-compliant switching and transmission systems in calling and called parties' countries will theoretically allow the called party to receive the CCITT-defined country code and the national telephone number of the calling party, a practical solution to the problem of OCI delivery to the international toll-free subscriber is not at hand in the foreseeable future. This conclusion stems from the fact that global implementation of the ISUP standards requires significant, costly and time-consuming enhancements to the switching and transmission systems of the worldwide telecommunications network. Furthermore, the practical implications of the strictness and stringency of the ISUP standards minimize the benefits of their full scale long-term implementation. The ISUP standards, for example, do not allow the international telecommunications network to forward only the Originating Country Code (OCC) portion of the CLI. Hence, until full CLI information can be forwarded from one country to another, no CLI information will be sent. The need for our invention takes greater importance when it is realized that partial implementation of the ISUP standards is unavailing since the presence of any non-ISUP compliant switches or non-CCITT7 compliant trunks in an international call path will prevent CLI forwarding.
Even if the ISUP standards are globally implemented, the problem of OCI delivery will still persist, because the ISUP standards specify a privacy option that enables the caller to prevent the display to the called party of his/her CLI information. Thus, the exercise of the privacy option by the caller prevents the calling party from receiving not only the calling party number, but also the OCC in the CLI, since only full CLI forwarding is allowed by the standards. Hence, even in the event of the future implementation of the ISUP standards, the problem of circumventing the undesirable side effects of the strictness of the standards still needs to be addressed.